No visable set screw?

I believe this to be kohler but can't find anything about them on Kohler site. no water passes through either hot or cold. i am trying to figure out how to remove handle with hope I can investigate why, This shower has not been used for at least 7 years but now house needs to be sold and it must work. Looks like some kind of web in the close up reflection of the back of handle. Please help! thanks